Catechuic acid and ethyl 2,4,5-trihydroxybenzoate from D-glucose.

Synthesis of catechuic acid (1) and ethyl 2,4,5-trihydroxybenzoate (2) from D-glucose-derived beta-ketoester is described. The polyhydroxylated beta-ketoester obtained from the hydrolysis of sugar beta-ketoester 3 was subjected to an aldol-type condensation to get 4 that on enolization, dehydration, and hydrogenation afforded ethyl 2,4,5-trihydroxybenzoate (2). On the other hand, hydrogenation of aldol product 4 afforded polyhydroxylated keto-carbasugar 6, which on mild acid treatment and ester hydrolysis in basic media led to catechuic acid 1. Intermediate 4 is co-related to 3-dehydroshikimic acid, a biochemical intermediate from D-glucose in the synthesis of pro-catechuic acid.